Ribbon cables for use with printed circuit boards typically have a series of electrical conductors embedded next to each other in an insulation material. The conductors can be round conductors with a circular cross section and/or flat conductors with a rectangular cross section. A plug-in connector housing for receiving such a ribbon cable has a cable plug-in opening to accept a ribbon cable end, and conductor contact receptacles to accept conductor contacts extending into the cable plug-in opening. The conductor contacts are electrically connected to terminal contacts that can be connected, for example, to the strip conductors of a printed circuit board by soldering.
In order to permit electrical contacting between the ribbon cable conductors and the conductor contacts of the plug-in connector, the ribbon cable conductors are exposed on one ribbon cable end, on a broad side of the ribbon cable, by stripping the insulation therefrom. The conductor contacts have contact regions with contact springs that engage the exposed ribbon cable conductors when the ribbon cable end is plugged into the cable plug-in opening of the plug-in connector. However, the ribbon cable end loses its bending rigidity upon the stripping of the insulation. This may hamper the inserting of the ribbon cable end into the cable plug-in opening of the plug-in connector, and may complicate electrical contact between the exposed ribbon cable conductors and the contact springs of the conductor contacts. To overcome these shortcomings, a reinforcement layer, preferably in the form of a reinforcement sheet, is applied on the broad side of the ribbon cable end on which the ribbon cable conductors are not exposed. This increases the bending rigidity of the ribbon cable end reduced by the stripping of the insulation. A material with relatively high intrinsic bending rigidity is typically used for such a reinforcement sheet.
Although this type of reinforced connector may operate with varying degrees of success in use, this type of reinforced connector is replete with shortcomings which detract from its widespread usefulness. More particularly, this type of ribbon cable has a sheet structure with a thickness of about 0.4 mm. Conventional plug-in connectors used for connection of ribbon cables have a limited design height of about 10 mm. Accordingly, from the beginning of the cable plug-in opening, to the spring contacts of the conductor contact, a lateral guide for the thin ribbon cable only exists over a short zone of about 7 mm. Also, conventional plug-in connectors for connection of such ribbon cables have significant manufacturing tolerances. Therefore, a ribbon cable end must be plugged into the cable plug-in opening of the plug-in connector with only limited guide depth and unreliable lateral guiding. The probability that such a reinforced ribbon cable end will be plugged in obliquely or even with kinks in the plug-in connector is extremely high. Because of the narrow spacing pattern of the ribbon cable conductors and the conductor contacts in the plug-in connector, inaccurate insertion can easily lead to an alignment situation in which the ribbon cable conductors are not properly brought in contact with the corresponding conductor contacts.
In addition to the foregoing, the force with which the contact spring arms of the conductor contacts engage the ribbon cable conductors is limited given the very limited size of the conductor contacts. Therefore, the ribbon cable conductors may loosen from the conductor contacts, even if a small tensile force is exerted on the ribbon cable.
There is a need for an improved plug-in connector for establishing a high reliability connection with a ribbon cable end.